Bioengineering functional copolymers. XIV. Synthesis and interaction of poly(N-isopropylacrylamide-co-3,4-dihydro-2H-pyran-alt-maleic anhydride)s with SCLC cancer cells

Novel antitumor active functional polymers with supramacromolecular structures were synthesized by a complex-radical terpolymerization of N-isopropylacrylamide (NIPAm), 3,4-dihydro-2H-pyran (DHP), and maleic anhydride (MA) with 2,2'-azoisobisbutyronitrile as a radical initiator in 1,4-dioxane at 65°C under nitrogen atmosphere. The structure and composition of terpolymers were investigated by (1)H ((13)C) NMR spectroscopy. Interaction of terpolymers with human lung small cell carcinoma (SCLC) were investigated by using different methods such as cytotoxicity, statistical, apoptotic and necrotic cell indexes, double staining and caspase-3 immunostaining, light and fluorescence inverted microscopy analyses. Investigations into structure, composition, and antitumor activity relationships revealed that terpolymers containing a combination of ionisable amide-pyran linkages and H-bonded carboxylic groups exhibited higher cytotoxicity. It was observed that terpolymer with nearly alternating structure provides a maximum concentration of ionisable and H-bonded antitumor sites, and therefore, exhibits higher in vitro cytotoxicity, apoptotic and necrotic effects towards SCLC cancer cells.     

Bioengineering functional copolymers. XXI. Synthesis of a novel end carboxyl-trithiocarbonate functionalized poly(maleic anhydride) and its interaction with cancer cells

A novel carboxyl-trithiocarbonate functionalized polymer with a highly selective antitumor activity was synthesized by a reversible addition-fragmentation chain transfer (RAFT) polymerization of maleic anhydride (MA) with benzoyl peroxide as an initiator and S-1-dodecyl-S-(α,α'-dimethyl-α″-acetic acid)trithiocarbonate as a RAFT agent with the aim to design and synthesize an effective anticancer agent with minimum side effects. The structure, molecular weights and composition of synthesized polymers were investigated by (1)H ((13)C) NMR, MALDI-TOF-MS and GPC analyzes. It was demonstrated that RAFT polymerization of MA was accompanied by a partially controlled decarboxylation of anhydride units and the formation of conjugated double bond fragments in backbone macromolecular chains. The mechanism of interaction of pristine RAFT agent and PMA-RAFT polymer with cancer (HeLa human cervix carcinoma) and normal (L929 Fibroblast) cells was investigated by using a combination of chemical, biochemical, statistical, spectroscopic (SEM and fluorescence inverted microscope) and real-time analysis (RTCA) methods. PMA-RAFT exhibited higher and selective cytotoxicity, apoptotic and necrotic effects toward HeLa cells at relatively low concentrations (around 7.5-75μgmL(-1), IC(50)=11.183μgmL(-1)) and toward Fibroblast cells at high concentrations (IC(50)>100μgmL(-1)). The observed highly selective antitumor activity render PMA-RAFT polymers as promising candidates for the utilization in cancer chemotherapy.     

Effects of grazing on plant species diversity and carbon partitioning in semiarid rangelands of northeastern China

Grasslands are one of the most widespread landscapes worldwide, covering approximately one-fifth of the world’s land surface, where grazing is a common practice. How carbon storage responds to grazing in steppes remains poorly understood. We quantified the effects of grazing on community composition and species diversity, and carbon storage in two typical grasslands of northeastern China, one in Horqin and the other one in Hulunbeier. In both grasslands, grazing did not influence plant species diversity. However, it substantially decreased aboveground carbon by 31% and 54% in Horqin and Hulunbeier, respectively. Fenced and grazing treatments showed a similar belowground carbon at both locations. The predominant carbon pool in the study grassland ecosystem was found in the upper 100 cm soil depth, from 98.2 to 99.1% of the total carbon storage. There were no significant effects of grazing on soil carbon neither in the whole profile nor in the uppermost 20 cm soil depth in the two study grasslands. Studies on the effects of varying rangeland management, such as region disparity and grazing systems, may have important consequences on species diversity and carbon partitioning, and thus on rangeland stability and ecosystem functioning.     

Application of magnetic techniques in the field of drug discovery and biomedicine

Magnetic separation technology, using magnetic particles, is quick and easy method for sensitive and reliable capture of specific proteins, genetic material and other biomolecules. The technique offers an advantage in terms of subjecting the analyte to very little mechanical stress compared to other methods. Secondly, these methods are non-laborious, cheap and often highly scalable. Moreover, techniques employing magnetism are more amenable to automation and miniaturization. Now that the human genome is sequenced and about 30,000 genes are annotated, the next step is to identify the function of these individual genes, carrying out genotyping studies for allelic variation and SNP analysis, ultimately leading to identification of novel drug targets. In this post-genomic era, technologies based on magnetic separation are becoming an integral part of todays biology laboratory. This article briefly reviews the selected applications of magnetic separation techniques in the field of biotechnology, biomedicine and drug discovery.     

Exposure of rainbow trout (Oncorhynchus mykiss) to magnetite (Fe3O4) nanoparticles in simplified food chain: Study on ultrastructural characterization

The widespread exposure of metallic nanoparticles to the aquatic ecosystem and its adverse impact on human life is the colossal concern worldwide. In view of this, this context was investigated to analyze microscopically the bioaccumulation and localization of magnetite (Fe₃O₄) nanoparticles in the cellular organelles of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) in aquatic conditions. Initially, Fe₃O₄ nanoparticles were absorbed on to Elodea (Elodea canadensis) and fed to molluscs (Melanopsis praemorsa). Fish were fed with the same molluscs, and then the intestines and liver were examined using light and transmission electron microscopy. Results showed that nanoparticles were present in the cytoplasm and other organelles of cells (mitochondrion and lysosome) by absorbing through microvilli of the epithelial cells of the tunica mucosa in the intestine. Further, nanoparticles passed through the vessels of the lamina propria of the tunica mucosa and reached to the sinusoids of the liver via blood circulation. It was then accumulated from the endothelium of the sinusoid to the cytoplasm of liver hepatocytes and to mitochondria and lysosome. The accumulation of nanoparticles in the epithelial cells, cytoplasm, mitochondria, and lysosome revealed the degree of transparency of the pattern with slight hesitation. In summary, this investigation contributed towards the understanding of the physiological effects of Fe₃O₄ nanoparticles on O. mykiss, which ascertains essentiality for sustainable development of nanobiotechnology in the aquatic ecosystem.     

Inverse folding of RNA pseudoknot structures

Background  

RNA exhibits a variety of structural configurations. Here we consider a structure to be tantamount to the noncrossing Watson-Crick and G-U-base pairings (secondary structure) and additional cross-serial base pairs. These interactions are called pseudoknots and are observed across the whole spectrum of RNA functionalities. In the context of studying natural RNA structures, searching for new ribozymes and designing artificial RNA, it is of interest to find RNA sequences folding into a specific structure and to analyze their induced neutral networks. Since the established inverse folding algorithms, RNAinverse, RNA-SSD as well as INFO-RNA are limited to RNA secondary structures, we present in this paper the inverse folding algorithm Inv which can deal with 3-noncrossing, canonical pseudoknot structures.     

4-Phenylbutyric Acid Plus Valproic Acid Exhibits the Therapeutic and Neuroprotective Effects in Acute Seizures Induced by Pentylenetetrazole

Neurochemical Research - Endoplasmic reticulum (ER) stress and apoptosis are implicated in the pathogenesis of epilepsy. Here we examine the effects of valproic acid (VA) plus 4-phenylbutyric acid...     

Patch-clamp recording of charge movement, Ca(2+) current, and Ca(2+) transients in adult skeletal muscle fibers

Intramembrane charge movement (Q), Ca(2+) conductance (G(m)) through the dihydropyridine-sensitive L-type Ca(2+) channel (DHPR) and intracellular Ca(2+) fluorescence (F) have been recorded simultaneously in flexor digitorum brevis muscle fibers of adult mice, using the whole-cell configuration of the patch-clamp technique. The voltage distribution of Q was fitted to a Boltzmann equation; the Q(max), V(1/2Q), and effective valence (z(Q)) values were 41 +/- 3.1 nC/&mgr;F, -17.6 +/- 0.7 mV, and 2.0 +/- 0.12, respectively. V(1/2G) and z(G) values were -0.3 +/- 0.06 mV and 5.6 +/- 0.34, respectively. Peak Ca(2+) transients did not change significantly after 30 min of recording. F was fit to a Boltzmann equation, and the values for V(F1/2) and z(F) were 6.2 +/- 0.04 mV and 2.4, respectively. F was adequately fit to the fourth power of Q. These results demonstrate that the patch-clamp technique is appropriate for recording Q, G(m), and intracellular [Ca(2+)] simultaneously in mature skeletal muscle fibers and that the voltage distribution of the changes in intracellular Ca(2+) can be predicted by a Hodgkin-Huxley model.     

De novo synthesis and cellular uptake of organic nanocapsules with tunable surface chemistry

Water-soluble organic nanocapsules were prepared from bottlebrush copolymers with triblock terpolymer side chains composed of a degradable inner block (polylactide), a cross-linkable middle block (poly(4-butenylstyrene)), and a functional outer block (poly(styrene-co-maleic anhydride)). Bottlebrush copolymers are macromolecules with a long linear backbone and shorter polymeric side chains densely grafted onto the backbone. Hollow cylindrical nanoparticles were prepared by peripheral cross-linking of the bottlebrush copolymers and subsequent selective removal of the core. Reactive anhydride groups of the outer functional layer allowed for the preparation of nanocapsules with tunable surface characteristics. Cellular uptake of negatively charged organic nanocapsules showed strong surface chemistry dependence. The presence of hydrophobic groups on the nanocapsule surface was necessary for their nonspecific association with the cell membrane and subsequent internalization by endocytosis. The length of surface grafted oligoethylene glycol chains also had a dramatic influence on the intracellular accumulation of nanocapsules. Macropinocytosis was shown to be the predominant pathway for the cellular uptake of organic nanocapsules.     

Madagascar Fish Eagle productivity in the Tsimembo-Manambolomaty Protected Area and surrounding habitat of western Madagascar

We monitored the productivity of the critically endangered Madagascar Fish Eagle Haliaeetus vociferoides inside and outside of the Tsimembo-Manambolomaty Protected Area (T-M PA), western Madagascar from 2010 to 2015. We recorded 14 breeding pairs inside and 13 outside T-M PA. The T-M PA and surrounding habitat hosted respectively 10 and six breeding polyandrous pairs, composed of one adult female and two adult males. During the six-year study period, 101 eggs were laid in nests in T-M PA of which 60 hatched and 58 young fledged. We recorded 62 eggs laid in nests outside the T-M PA of which 39 hatched and 36 young fledged. Productivity was similar at both sites, inside and outside T-M PA, with 0.84 (58/69) and 0.76 (36/47) fledgling per nesting attempt and 0.69 (58/84) and 0.5 (36/72) fledglings per territorial pair, respectively. Polyandrous pairs have higher productivity compared with normal pairs. Threats to Madagascar Fish Eagles and their habitat were low due to the existence of a community-based resource management system called the Local Management Secured System (GELOSE) inside and outside the T-M PA. This system is based on strengthening local traditional customs and rules, and involving local people in managing their natural resources sustainably along with biodiversity conservation.